/// <summary>
/// Query a service on it's predefined 'ping' endpoint.
/// </summary>
private async Task <ServicePingResponse> QueryService(Service service)
{
var pingUrl = service.Endpoint.TrimEnd('/') + "/ping";
var sw = Stopwatch.StartNew();
try
{
Logger.LogInformation($"{nameof(QueryService)}: Querying '{pingUrl}'...");
var response = await _webRequest.ExecuteRequest(
endpoint : pingUrl,
method : HttpMethod.Get,
retries : 0);
sw.Stop();
Logger.LogInformation($"{nameof(QueryService)}: Service '{service.Identifier}' responded in {sw.Elapsed}");
return(ServicePingResponse.Create(service.Identifier, sw.ElapsedTicks, IsSuccessStatusCode(response)));
}
catch (TaskCanceledException)
{
// Exception handling is managed in our IWebRequest service.
}
catch (Exception ex)
{
Logger.LogError(ex, ErrorMessage(ex));
}
string ErrorMessage(Exception ex) => $"{nameof(QueryService)}: Failure querying service '{service.Identifier}' at '{pingUrl}'; {ex.GetBaseException().Message}";
return(ServicePingResponse.Create(service.Identifier, sw.ElapsedTicks, isSuccessStatusCode: false));
}
/// <inheritdoc/>
public ServicePingResponse AddServicePingResponse(string identifier, ServicePingResponse servicePingResponse)
{
if (string.IsNullOrEmpty(identifier))
{
throw new ArgumentNullException(identifier, "Cannot be null");
}
var cacheKey = _serviceStateCacheKey(identifier);
if (!_cache.TryGetValue(cacheKey, out Queue <ServicePingResponse> cachedResponses))
{
throw new Exception($"Cache entry for service '{cacheKey}' not found");
}
cachedResponses.Enqueue(servicePingResponse);
if (cachedResponses.Count > PING_RESPONSE_CACHE_SIZE)
{
cachedResponses.TrimExcess();
}
return(servicePingResponse);
}
/// <inheritdoc/>
public IEnumerable <ServicePingResponse> GetServiceState(params string[] identifiers)
{
if (identifiers == null || identifiers.Length == 0)
{
throw new ArgumentNullException("Service identifier cannot be null or empty");
}
var response = new ServicePingResponse[identifiers.Length];
for (var i = 0; i < identifiers.Length; i++)
{
var serviceCacheExists = _cache.TryGetValue(_serviceStateCacheKey(identifiers[i]), out Queue <ServicePingResponse> serviceStates);
if (!serviceCacheExists || serviceStates.Count == 0)
{
continue;
}
// Return the last, most recent ping response.
response[i] = serviceStates.Last();
}
return(response);
}
